FOOD, FACTS and FADS

Exploring the sense and nonsense of food and health


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Sugar Blues?

Sugar or fat? It appears that we have not had all the  research information to decide whether sugar or fat is associated with heart disease. Shame on the industry and the academics who participated back in the 1970’s and 80’s.

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How the Food Industry Influences Nutrition Research

Industry funded studies are becoming a major influence on nutrition research that is already considered by some to have some important design limitations.

Headlines often proclaim that certain foods have healthy benefits not supported by science. These are used as marketing tools by the companies to describe their products in terms of what is described as a “health halo.” This practice contributes to false claims and the dissemination of nutrition misinformation which is already abundant.

One reason is that research in nutrition is not very well funded by very many sources; therefore, food companies often do provide the funds and at the same time gain their own benefits, i.e., increase their profits.

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Nutrition Research 101

Why is Nutrition Research so Difficult?

The Scientific Method 101

Ideally advances in nutrition are made using the scientific method. In case you can’t readily recall your last biology class, here it is in its most simple form:

  • The first step is to make an observation, e.g. more people get colon cancer in the U.S. than in Japan
  • Next, explanations are proposed and called a hypothesis, e.g. The lower incidence of colon cancer in Japan compared to the U.S. is due to diet differences.
  • To test the hypothesis, experiments are designed. Compare the diets and incidence of colon cancer in a Japanese American population compared to a U.S. Caucasian population.

If the results from  repeated experiments support the original hypothesis, a theory can be developed. if not, the hypothesis is rejected.

Simple, right? Not in nutrition. Why is nutrition information so confusing or contradictory? Here are some reasons why. This post only presents a few basic problems in nutrition research; it is not meant to be a comprehensive guide.

  1. You cannot keep people in a bubble.

Evidence-based nutrition should ideally be based on the randomized, placebo-controlled clinical trial using large population samples and extending the intervention for a reasonable time to measure health outcomes. Typically, one group is given a certain diet to follow; another group is given no particular diet but allowed to eat anything they choose. A randomized controlled trial (RCT) can provide sound evidence of cause and effect if the many variables are controlled.  These studies are just not practical for long-term nutrition interventions.  They are expensive long-term and have another important limitation. People are notorious for cheating on their assigned diets, and compliance is always difficult.

  1. Most nutrition information comes from observational studies.

Many nutritional studies are observational studies that attempt to assess how changes in diet affect health by looking at correlations or associations between what people report they eat and how many develop a particular disease.  When many observational studies reach the same conclusions, there is enough evidence to suggest  dietary recommendations. These types of studies only show correlation or associations, not cause and effect.

There is another problem with observational studies. They typically depend on surveys where people report what they ate the day (or week) before. This type of data reporting is known to be extremely unreliable. Researchers have long known that people misreport or forget, intentionally and unintentionally, what they eat.

 3. People and foods are different.

People obviously differ physiologically, psychologically, and genetically. This is shown in studies that measured people’s blood sugar responses to the same foods and found vast fluctuations. Also foods  differ in quality, content, preparation and other unknown characteristics, e.g. how they were grown or processed.

4. Conflict of interests and bias add to the confusion.

Food companies often try to conduct studies that promote the claimed health benefits of their products. They often use studies that support their claims as major marketing tools.

  1. Replication as part of the scientific method is often neglected.

There is always a chance that the original results may have occurred due to error. To alleviate this possibility, it is common if possible, to repeat the original experiment multiple times. This also is prudent when the original results are significant or surprising.

What Can You Do?

So, should you just give up on listening to anything about the food you eat? We should be reminded that “all scientific knowledge is subject to change. We learn from it.” We can learn from both negative results as well as positive results.

By looking at the big picture of  many studies (meta-analyses) and not just a few on a certain nutrition question, you can begin to see patterns that point to the same direction. It is extremely important to not dwell on single nutrient studies, but on studies that examine the total diet.

Pay attention to the source of funding and the potential biases of the authors. Do not pay attention to bold statements or scaremongering headlines that are not supported by the current research. Is it selling something? Is it based on someone’s personal story (anecdotal)?

Was the information interpreted accurately? Compare the news headlines with the peer-reviewed conclusions of the study information. Did the study discuss its limitations? Were the results or the conclusions of the study twisted in a way to support the bias of the author(s)? Has the importance of the study been exaggerated? Does it make sense?

 

 

 

 


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The Search for a “Healthy Diet”

By Sally Feltner, PhD, MS, RDN  March 18, 2017

Does your doctor often say, “Watch your diet” or have you noticed that most diet advice recommends that you eat “a healthy diet.” But honestly, why should we believe anything nutrition scientists have to say at this point? There’s been little consistency in the advice we’ve been given for decades. We have gone from hearing advice, to advice, that contradicts the first advice, and now we’re back in some cases to the original advice again. A lot of that advice has even turned out to be actually harmful. Remember the recommendation in the middle 1990’s to switch to trans-fat laden margarines

When I first began to study nutrition in the 1980’s, we knew little about the causes of cancer, heart disease, and diabetes as well as dementia, bone loss, you name it. I have been through the low fat, the low carb, the high fiber, the whole grain, the low fat dairy eras etc. . as well as just about any fad diet or gimmick you could think of. What have we learned? Not much. We are still searching for the perfect diet, the magic supplement, the best “superfood” to keep us healthy and increase our lifespan.

This is not to say that there have not been any important discoveries. Back in the early days of nutrition research, the discovery of vitamins and minerals saved thousands of lives. We have clearly eliminated the deficiency diseases, at least in developed countries, of scurvy, beriberi, pellagra as well as the prevention of goiter (iodine). More recently, we learned to prevent the devastating effects of neural tube defects with the fortification of folate in grain products.

Recently, the latest rankings of the U.S. News and World Report 2017 Best Diet Rankings were published. The three best diets overall as well as the three best diets for healthy Eating were:

These three diets are important because each one has been shown be associated with positive health benefits. The DASH diet benefits are associated with blood pressure control and thus an decreased heart disease risk. The Mediterranean diet has heart benefits and improved cognitive (Alzheimer’s) health, and the aim of the MIND diet is a combination of the other two diets – the DASH and Mediterranean that zeroes in on foods in each that specifically affect brain health. Both the Mediterranean diet and the MIND diet won honors in easiest to follow, important with any diet attempt. There is no sense to attempt a diet you cannot feasibly follow. It  should not be a “diet”, but a lifestyle.

Nutrition professionals need to be careful about how we support what we say. Instead of “we know,” we have to just admit that “we think.” People often become resentful when we pretend to know more than we really do and tell them what to eat and then have to backtrack on that advice years later.

Fortunately, there are other says to assess diet quality. For now, we also can rely on the observational studies that look at the traditional diets of certain populations and cultures have shown us the many lifestyles factors including diet that confer health and longevity.


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The Problem with Nutrition Research

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This article is very long, but it is easy to get the point. If you choose to not read the whole article, the video at the end tells us about a major problem with some nutrition studies. There is also may be the influence  of a conflict of interest and industry funding.  Unfortunately, I wish this was not a problem, but it is what it is.  Nevertheless, the quest continues to find the “perfect” diet.  Good health and longevity is based on a complex interaction of many factors, not just diet and that is why we study healthy cultures such as found in the book “The Blue Zones.”  By doing so, we can begin to understand the complex environmental and cultural factors and how they interact to keep us healthier and possibly enjoy long lives.

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